1. Field of the Invention
The present invention relates to a semiconductor device including an oxide semiconductor film and a manufacturing method thereof.
In this specification, a semiconductor device refers to all devices which can function by utilizing semiconductor characteristics; an electro-optical device, a semiconductor circuit, and an electronic apparatus are all included in the category of the semiconductor device.
2. Description of the Related Art
In recent years, transistors which are used for many liquid crystal display devices and light-emitting display devices typified by flat panel displays have been formed over glass substrates and using a silicon semiconductor such as amorphous silicon or polycrystalline silicon.
Instead of the silicon semiconductor, a technique in which an oxide semiconductor that is metal oxide having semiconductor characteristics is used for transistors has attracted attention.
For example, techniques in which a transistor manufactured using zinc oxide which is single-component metal oxide or In—Ga—Zn—O-based oxide which is a homologous compound as an oxide semiconductor is used as a switching element or the like of a pixel of a display device, is disclosed (see Patent Document 1 to Patent Document 3).